He married the former Josephine Cook "Jo" Fraser of Seattle, Washington on February 23, 1946; she was the step-daughter of Admiral James L. Holloway, Jr..[6] They had two children: Walter M. Schirra, III, born June 23, 1950 and Suzanne, born September 29, 1957.[6][7] Jo Schirra died April 27, 2015.[8]

After spending time as a flight instructor and carrier based aviator, he later returned to his test pilot duties and helped evaluate the F-4 Phantom II jet fighter for Naval service. In the image at left, Schirra is shown taking delivery of a F3H Demon from McDonnell Aircraft Design Chief, Dave Lewis. They remained good friends, later working together on the McDonnell Mercury 7 program.

In 1959, Schirra was one of 110 military test pilots selected by their commanding officers as candidates for the newly formed National Aeronautics and Space Administration's Project Mercury, the first U.S. manned space flight program. Following a gruelling series of physical and psychological tests, on April 2, 1959, Schirra was chosen as one of the original seven American astronauts. Schirra's special responsibility in Project Mercury was the development of environmental controls or life-support systems that would ensure the safety and comfort of the astronaut within the spacecraft during the mission. His tasks also included the testing and improvement of the pressurized suit worn by the astronauts.

On October 3, 1962, Schirra became the fifth American in space, piloting the Mercury-Atlas 8(Sigma 7) on a six-orbit mission lasting 9 hours, 13 minutes, and 11 seconds. The capsule attained a velocity of 17,557 miles per hour (28,255 km/h) and an altitude of 175 statute miles (282 km), and landed within 4 miles (6.4 km) of the main Pacific Ocean recovery ship. On October 16, 1962, Schirra and his family were greeted by President Kennedy at the White House, just hours after Kennedy received information leading to the Cuban Missile Crisis.

On December 15, 1965, Schirra flew into space a second time as Command Pilot of Gemini 6A, with Pilot Tom Stafford. Gemini 6, originally scheduled to launch on October 25, was planned to perform the first space rendezvous and docking with an unmanned Agena target vehicle launched separately, but the Agena was destroyed in a launch failure. It was decided to defer launch of the alternate mission 6A to after the December launch of Gemini 7, during which Schirra would perform rendezvous, but without docking. During the first rescheduled launch attempt, the booster rocket unexpectedly shut down seconds after ignition and did not launch. Although mission rules called for the crew to eject from the spacecraft in that situation, Schirra used his pilot's judgement and did not eject, as he had not detected any upwards motion. This turned out to be the correct call for their personal safety. The flight was launched successfully three days later, and Schirra successfully performed the first rendezvous with Gemini 7 containing astronauts Frank Borman and James Lovell, station-keeping his craft to distances as close as 1 foot (30 cm). Gemini 6 landed in the Atlantic Ocean the next day, while Gemini 7 continued on to set a 14-day manned space record.

While on the Gemini mission, Schirra played a Christmas practical joke on the flight controllers by first reporting a mock UFO (implying Santa Claus) sighting, then playing "Jingle Bells" on a four-hole Hohnerharmonica he had smuggled on board, accompanied by Stafford on sleigh bells.[10] Hohner subsequently produced a "Wally Schirra" commemorative model.

In late 1966, Schirra was assigned to command a three-man Apollo crew with Donn F. Eisele and R. Walter Cunningham to make the second manned flight test of the Apollo Command/Service Module some time in 1967, after the first such flight to be made by Gus Grissom, Edward White and Roger Chaffee. But soon after, this second test flight was considered unnecessary, and Schirra's crew was reassigned as Grissom's backup. But in January 1967, Grissom and his crew were killed in a cabin fire during a ground test of Apollo 1. Schirra's crew was thereby promoted to prime crew of the first manned flight. This became Apollo 7 in the program's revised mission numbering plan, and was delayed to the fall of 1968 while safety improvements were made to the Command Module.

Schirra, like most of the Mercury and Gemini astronauts, had come to gain a sense of security from the Pad Leader responsible for the spacecraft's launch readiness, an extremely diligent, uncompromising McDonnell Aircraft employee, Guenter Wendt. But since the Apollo contractor was North American Aviation, Wendt was no longer pad leader. After the Apollo 1 accident, Schirra felt so strongly he wanted none other than Wendt as pad leader for his Apollo flight, that he pulled strings with his boss Deke Slayton and North American's launch operations manager Bastian "Buzz" Hello to hire Wendt so he could be Apollo 7 pad leader. Wendt remained pad leader for the remainder of the Apollo and Skylab programs, and stayed on with NASA into the Space Shuttle program before retiring.[11]

Schirra looks out the window in front of the commander's station on Apollo 7

Apollo 7 was launched on October 11, 1968, making Schirra the first person to fly in space three times. Schirra, Eisele and Cunningham spent eleven days in Earth orbit, performed space rendezvous exercises with the upper stage of the Saturn 1-B launch vehicle that sent them into space, and provided the first live television pictures publicly broadcast from inside a manned spacecraft, for which Schirra received an Emmy Award. (An experimental TV transmission had been made during Gordon Cooper's Mercury flight in 1963, but this was not broadcast to the public.)

During the mission, Schirra caught what would become perhaps the most famous head cold in NASA history.[6] He soon passed the cold to Eisele, and the crew became known for their grumpy exchanges with Mission Control. Schirra had made the decision before launch to retire after this flight, and left the NASA Astronaut Corps on July 1, 1969.[6]

Schirra's logbooks show a total of 4,577 hours flight time (including 295 in space) and 267 carrier landings.

A combination of pseudoephedrine decongestant with triprolidine antihistamine was the cold medicine carried on board the Apollo missions and prescribed by the flight surgeon. Years later when this became available over the counter as Actifed, the makers of Actifed hired Schirra as a television commercial spokesman, based on the notoriety of his Apollo 7 in-space head cold.[6]

In January 1979, Schirra formed his own firm, Schirra Enterprises, and he worked as a consultant in 1979 and 1980. In 1980, he was elected to the Board of Directors of Electromedics Incorporated. He has also served as President of Prometheus, an energy development company in Colorado, and on the Board of Directors of Kimberly-Clark, Finalco and Net Air International. In 1984, he and the other surviving Mercury astronauts and Gus Grissom's widow, Betty Grissom, founded the Mercury Seven Foundation to raise money for scholarships for science and engineering students in college. In 1995, the organization was renamed the Astronaut Scholarship Foundation.[6]

In 1988 (republished in 1999) Wally Schirra, with Richard N. Billings, released his first autobiography Schirra's Space.

In 1995 Schirra co-authored the book Wildcats to Tomcats: The Tailhook Navy with fellow Navy Captains Richard L. (Zeke) Cormier, and Phil Wood, with Barrett Tillman as the writer. It has a section by each of these Naval Aviators that cover five decades of flight experiences, including combat tours in World War II, Korea & Vietnam.

In 2005 Schirra co-authored the book The Real Space Cowboys with Ed Buckbee. The book is an account of the 'Mercury Seven' astronauts. It follows them through the process of selection for the program, their entire careers, and into retirement. Wernher von Braun, NASA, Space Camp, and the U.S. Space and Rocket Center are given special attention.

Schirra was also a major contributor to the 2007 book, In the Shadow of the Moon, which captured his final published thoughts on his life and career.

Schirra was mentioned in the second episode of WKRP in Cincinnati. The "Pilot Part 2" episode from 9/25/1978, featured the Station Manager, Arthur Carlson saying that his maid believed Wally Schirra was controlling her mind and she believed she had to store up foods.

In an episode of The Venture Bros, Wally is mentioned as having participated in a threesome with recurring fictional character Colonel Gentleman, and Gore Vidal. In a later episode, he is again referenced by Gentleman in a flashback, who expresses concern for his participation in a potentially sabotaged Apollo mission.